Speaker unit



Oct. 20, 1936. w ELLMORE I 2,058,071 SPEAKER UNIT Filed July 2, 1954 2Sheets-Sheet 1' Oct.20, 1936. w. A. ELLMOR E 2,058,071

. r SPEAKER UNIT I Filed July 2, 1934 2 Sheets-Sheet 2 Patented .0...20, 1-936 v SPEAKER UNIT William A. Ellmore, Wilmette, 1u., assignor toUtah Radio Products Company, Chicago, 111., a

corporation ofv Illinois Application July 2, 1934, Serial No. 733,365

4 Claims. (Cl. 179-119) The invention relates generally to devices fortransforming electrical vibrations into sound vibrations and moreparticularly to a device of the type generally known as a magneticspeaker.

A general object of the invention is to provide a. novel device of thischaracter having an improved arrangement and relationship of parts bywhich simplicity of manufacture, ease of assembly, and accuracy ofadjustment are achieved.

Another object is to provide a device having high operating efficiency.

Another object is to provide a new and improved device wherein the voicecoil is disposed in substantially the closest possible relation to thearmature which is responsive to: the energizations thereof whereby toobtain maximum efiiciency in operation.-

vibrated, andfor obtaining accurately the precise relationships requiredin the assembly of the several elements comprising the cone drivingmechanism.

Other objects and advantages will become apparent in the followingdescription and from the accompanying drawings, in'which:

Figure 1 is a fragmentary rear view in elevation of a device embodyingthe features of the invention.

Fig. 2 is an enlarged fragmentary centralsection through the devicetaken along the line 2-2 of Fig. 1.

Fig. 3 is an enlarged view showing a detail of the cone mounting orsupporting member.

Fig.4 is a distended view in perspective of the several elements forminga part of the means by which the armature is supported.

Fig. 5 is a fragmentary sectional view of the cone driving mechanismtaken as indicated by the line 55 of Fig. 6, the cone support beingomitted for clarity.

Fig. 6 is a sectional view of said mechanism taken along the irregularline 6-6 of Fig. 5.

Fig. '7 is a sectional view of said mechanism taken transversely thereofon the line Fig. 5.

and what may be termed a motor or driving Fig. 8 is a fragmentaryperspective view of the armature'and pole piece assembly.

Fig. '9 is an exploded view showing the several elements constitutingthe adjustable mounting of the armature. While the invention issusceptible of various modifications and alternative constructions, Ihave shown in the drawings and will herein describe, in detail thepreferred embodiment, but it is to be understood that I do not therebyintend to limit the invention to the specific form disclosed, but intendto cover all modifications and alternative constructions falling'withinthe spirit and scope of the invention as expressed in the appendedclaims.

In devices of the type to whichthis inventionrelates, the speaker unitconventionally embodies a suitably supported sound vibration producingmeans, generally designated in in the drawings,

means, indicated at l l, by which electrical vibrations are transformedinto mechanical vibrations and transmitted to the sound vibrationproducing means. The desired result is, in the present device, producedby theeifect of a permanent magnetic field upon a movable armature whichis variably magnetically energized by varying or alternating electricalcurrents passing through an associated voice coil, the responsivemovements of the armature being suitably transmitted to the dei/ice forproducing sound vibrations.

With particular reference to Figs. 2,5 and 6, a preferred. form ofdriving means ll embodies the following structure and arrangement ofparts. A flat base i2, preferably of elongated, somewhat oval shape,.has outstanding from one side thereof integrally formed supports orposts l3 which may be rectangularly arranged as shown. These postssecure what may be termed a pole piece assembly to the base indefinitely 40 fixed relationship thereto. The pole piece assemblycomprises a pair of spaced-plates M, l5 which support therebetween apair'oi pole pieces l6,. l6. Each pole piece,'as shown in Figs. 2 and'6,preferably consists of a stack of lamina-.- tions which aresubstantially .U shaped (see Fig. 2). 0n the outer sides of the legs ofeach lamination are projecting nibs l'l providing elongated ribsOnthecomplete pole assemblies or pole? pieces which are fashioned forengagement with slots lilprovided in the spaced plates I4, I 5. Theslots are so formed as to receive the ribs snugly: whereby precisely andsecurely to mount tliepole pieces between the supporting plates.

fine a channel which has a central transverse gap and faces along themajor dimension of the supporting plates and base. In assembly, one ofthe supporting plates, in this instance the plate i4, abuts the base l2and the corners of said plate are cut away to clear the posts l3. Theother plate overlies the posts and is apertured to allow screwthreadedextensions ill on the posts to pass therethrough. Nuts 23 threaded ontosaid extensions rigidly secure the pole piece assembly to the base. Ifdesired other screws 23' through the base and engaging the base abuttingplate l4 may be employed finally to secure the parts permanentlytogether.

While the pole pieces l3, l6 may be magnetically energized in anysuitable manner to produce a permanent magnetic field therebetween thepresent embodiment attains this end by means of a pair of permanent.magnets 2| which are U shaped and are of somewhat greater overalldimensions than the base I2. The magnets are disposed in end to endrelation with their like poles abutting and with their meeting faceslocated substantially on the transverse median line of the pole pieces,as shown in Fig. 6. Thus, the pole pieces l6,- Iii have oppositepolarity and the magnetic attraction between each magnet and the polepieces is ample to hold the magnets in place against endwise movementoutwardly. The magnets rest against the base i2 at one side and the openface defined by the other side thereof may be suitably closed and themagnets held in place by a cover member 22 (Fig. 5) which is preferablysecured by nuts 23 threaded onto the extensions IQ of posts l3.

The structure thus far described comprises the means by which apermanent magnetic field is produced in the present device. Operativelylocated within this field is an armature having a voice coil closelyassociated therewith so that the armature will be magnetically energizedin accordance with electrical current variations passing through thevoice coil. The attraction and repulsion action resulting from suchvariable magnetization of the armature in the permanent magnetic fieldcauses the armature to move accordingly. As may be seen clearly in Fig.5, the armature comprises a stack of laminations 24 of rectangular formwhich are secured together by pins 23 passing therethrough from end toend. The armature is dimensioned substantially to fill the space betweenthe pole pieces but is of slightly less thickness than the width of thespace between the pole pieces to provide a relatively small clearancebetween each side of the armature and the pole piece opposed thereto.

The armature is surrounded by a voice coil, the structure of whichpreferably comprisesa supporting case 26 of a thin dielectric materialformed to provide an outwardly facing channel within which a number ofturns of wire 21 are wound. The case 23, as shown in Fig. 6, iscentrally open to'fit closely yet loosely about the armature and isdimensioned to fit snugly (see Figs. 2 and 8) within the channel definedby the U-shaped pole pieces l6 and I3. This snug fit positions thjevoicecoil against other than longitudinal movement of the coil assemblythrough the channel. To prevent longitudinal movement, lugs 23outstandingfromthe voice coil case 23 are provided for engagement withthe opposite side faces of at least one of the pole pieces. Thus, thevoice coil assembly may be definitely and accurately fixed with respectto the pole pieces.

The armature 24 must be supported in accurately spaced relation betweenthe active faces of the pole pieces. In the present embodiment the meansfor supporting the armature not only rigidly'secured thereto by the pins23. The arms I project in this instance through registering apertures 3|in the base l2 and supporting plate l4. Overlying the outer face of eacharm 29 and end portion 33 is a plate 32 which is rigidly secured to theassembly by the pins 23 and by rivets 33 or the like. Each of the plates32 carries a brir' Te-like member 34 in the form of a U-shaped structurehaving diverging arms and dimen- :ioned to fit over or straddle thevoice coil strucure.

The assembly of one of the plates 32 with its bridge member 34 is bestshown in Fig. 4 and is relatively important since it provides a simplebut exceedingly accurate means for securing these parts together. Thus,the plate 32 has apertures 35 and 33 through which the rivet 33.and pins23 respectively extend in securing the plate to the armature assembly.The end of the plate opposite that at which the aperture 33 is locatedhas an intermediate end recess 31 providing spaced longitudinallyextending nibs 33. One diverging leg ofthe bridge member 34, which legis designated 33, has notches 43 out in its opposite side faces near theend thereof to receive the nibs 33 when the parts are moved together atright angles to each other. The other diverging leg, designated 4i has acentrally located end projection 42 which is adapted to be receivedwithin an aperture 43 appropriately formed-on the plate 32. Thus, whenthe nibs 33 and notches 43 are engaged and the bridge member forcedsideways to position the projection 42 in the aperture 43, a bindingengagement between the nibs 33 and the margins of the notches 43results. The projection 42 may then be secured to the plate 32 in anysuitable manner, as by soldering, to complete the assembly. Inconsequence, the bridge member 34 may be secured to the plate 32 in avery simple manner which nevertheless insures that all necessaryaccuracy will be obtained.

Each bridge member 34 has a flat base portion designated 44 whichcontains spaced apertures 43 adapted to receive tongues '43 on a fiatbar 41. A permanent connection between these parts is obtained inanysuitable manner as by soldering. The bars are arranged to extendoutwardly from the base 44 at right angles thereto; and to the plate 32,and the parts are arranged so that the longitudinal line of the bars 4!lies substantially thereof has an.outstandingvlug48 acrosswhich thebars. 41: extend: The, lugs: and the I mounting means associatedtherewith are substantially identical and only oneconstructionwill-therefore v I be described.

l l The outer. face of a semi-circular recess49 (Figs. land 9) adaptedto receive a semi-cylindrical bearing 50. The cen-. ter onJwhich thearcuate surfaces ofthe recess and bearing are formed is substantiallythe pivotal axis of thearmature. Opposite the arcuate each log 48 isprovided with surface on the bearingis a channel 5| dimen sioned snuglyto receive the bar 4]. Opposed recesses 52 are provided in the sides ofthe channel to receive lugs 53 formed on a plate 54 which is arranged tooverlie the bar 41 after it has been positioned in the channel. -Abinding plate 55 is secured to the lug 48 by screws 56 and the plateextends across the recess 49 in the lug for engagement with the outerface of the plate 54.

With respect to the operation of mounting the armature structure andadjusting the position of the armature relative to the pole pieces, thebar is positioned in the channel 5| between the bearing 50 and the plate54, the bearing is placed in the recess 49, and the binding plate, bymeans of the screws 56, is caused to engage the outer face of the plate54. It will be evident that by tightening or loosening one or the otherof the screws-56, a' slight rotational movement of the bearing 50in therecess 49 may be produced and this movement is utilized to adjust thearmature to a desired operative position between the opposed faces ofthe pole pieces. As may be seen in of the cone mounting between theapexand the Figs. 5 and 9, the bearing 50 is somewhat longer than thethickness of the lug 48 to permit adjustment of the position of thebearing and its cooperating plate 54 along the length of the bar 41.-

Since movement of the armature produces a torsional strain in the bars41, the resistance which is offered to movement by the armature may beadjusted to a proper value by locating the bearing 50 at a proper pointalong the bar 47,.

It will be evident from the foregoing that the armature may thus beaccurately set in its proper operating position with respect to the polepieces and that the resistance to movement imposed on the armaturemay beeasily and accurately adjusted.

The arms 29 which extend outwardly from the armature assembly beyond thebase l2 converge. as maybe seen in Fig. 5, and at their outer ends arejoined by plates 51. From these plates a short link 58 extends at rightangles for connection with theapex of a cone 59 which hereinconstitutes-the sound vibration producing means Hi. This cone issupported by a generally conventional cone mounting in the form of astamping 60 to which the marginal edge of the cone is suitably connectedas at 6|. The cone mounting is generally conical, has a cup-shaped apex.

and is fashioned to extend about the rear face of the cone. A portion ofthe mounting near the apex thereof is struck outwardly and offset rearwardly, as at B2, to terminate in a fiat portion 63. Other portions,designated 64, are struck out rim thereof to" provide flat. surfaceswhich are substantially parallel to the struck-outpart 63.

The base l2 on its outer surface thereof has an upstanding lug 65intermediate its ends and near one side of the base and has otheroutstanding lugs 66 spaced longitudinally of the base adja- J cent tothe other side thereof. The arrangement 4 of these parts is such thatthe struck-outpertion 63 is disposed outside of and in abutment with thelug 65, while the struck-out portions 64 are in abutment .with theouter, sides of the lugs mounting from the base or frame of the drivingmechanism and the assembly is exceedingly rigid. If desired, aninsulated distributor BBfor cooperation with the, lead wires from thevoice coil may be secured to the lug 65 by the associated screw 61.

It will be seen from the foregoing that a speaker unit has been providedwhich embodies an improved arrangement of structurcand a novelaryrangements of parts.

structurally, the various elements which comprise the unit are capableof being produced by simple manufacturing processes. The assembly of thevarious elements into a complete structure may be easily accomplished gand once the parts have been assembled, the only formed by said magnetswith the bases thereof abutting the magnets and crossing the line ofengagement between the magnet ends, said pole members being opposed'butspaced from each other and the legs thereof defining a channel extendinglengthwise of the magnet assembly, an armature in the space between thepole members, a voice coil assembly located in said channel andencircling said armature with the coil in closely and symmetricallyspaced relation thereto throughout, said voice coil assembly having asnug fit in said channel and having means thereon interengaging a polemember to prevent movement thereof longitudinally of said channel,supporting means secured to said armature at each end and straddlingsaid voice coil structure, a frame supporting said magnets and polepieces, adjustable means for connecting said supporting means withsaidframe, a sound vibration producing device, and means for operativelyconnecting said armature'with said device including arms connected withopposite ends of said armature.

2. In a speaker, the combination of means providing a permanent magneticfield, a stack of laminatlons constituting an armature located in saidfield and having a voice coil in closely encircling relationshipthereto, and means for operatively supporting said armature including aplatesecured to each end of the armature and extending beyond theopposite sides thereof, one extending end having alined notches inopposite sides thereof and the other end being substantially centrallyapertured, a U-shaped bracket for each plate having diverging side armsand adapted to pass about the voice coil at that part of the assembly,one side arm having nibs fashioned to fit into said alined notches uponinsertion in a direction substantially at right angles thereto and toperfect a binding engagement between the parts when the other end isengaged with said plate, said last mentioned end having a partengageable within said aperture for securing the parts together, anoutwardly extending arm fixed centrally to each bracket and extendingtherefrom substantially on the center line of the armature assembly,means connecting with said arms for operatively supporting said armatureassembly, and means connected with said brackets and extendingsubstantially at right r angles to said arms for connection with a sound10 vibration producing device.

3. In a speaker, the combination of means for producing a permanentmagnetic field, an armature located in said field and having a voicecoil in closely encircling relationship thereto. and means foroperatively supporting said armature including a plate secured to 'abuteach end of the armature and to extend beyond the opposite sidesthereof, one extending end having alined notches in opposite sidesthereof, a U-shaped bracket for each plate having diverging side armsand dimensioned to pass about the voice coil at that part of theassembly, one side arm having nibs fashioned to fit into said aline'dnotches upon insertion in a direction substantially at right anglesthereto and to perfect a binding engagement between the parts when theother end is secured to said plate. and means fixed to each bracket andextending therefrom substantially on the center line of the armatureassembly for operatively supporting said armature assembly.

4. In a speaker, the combination of means for producing a fixed magneticfield, a stack of laminations constituting an armature located in saidfield and havinga voice coil in closely encircling relationship thereto,and means for operatively supporting said armature including a platesecured to the armature abutting each end thereof, a U-shaped bracketfor each plate having side arms dimensioned to pass about the voicecoil. means for securing said brackets to said plates. means connectedwith said brackets for operatively supporting said armature, and meansconnected with said brackets and extending substantially at right anglesto said armature for connection with a sound vibration producing de-

